The development of modern surgery began when doctors started administering anesthesia to the patients before and during surgical procedures. Anesthesia blocks or removes sensation particularly the feeling of pain, allowing the surgeon to perform surgery without patients experiencing extreme distress and pain they would otherwise undergo. Anesthesia produces a medically induced coma and a loss of protective reflexes from one or more medications resulting in amnesia, analgesia, muscle relaxation and sleep.
In standard operating rooms, an anesthesiologist administers general anesthesia through large machines that are connected to the patient's respiratory system. Drugs used to induce general anesthesia are administered through inhalation and/or injection. Most commonly, anesthesia is induced by injection and maintained through inhalation.
During general anesthesia, the patient is not breathing on his own, but through a closed system of the anesthesia machine. The most common type anesthesia machine is a continuous flow which is designed to supply oxygen, anesthetic drug as a gas and ambient air to the patient. As a closed system, respiratory parameters are easily monitored. Not only is the amount of anesthetic drug accurately monitored, but also many parameters such as oxygen saturation, as well as inspired and expired gases. The anesthesia machine, because of its complexity, size and infrastructure requirements, is typically rooted to the traditional operating room.
Now many medical procedures, both surgical and non-surgical, are performed outside the operating room in various hospital suites, ambulatory surgical suites and doctors' offices. Most procedures performed outside of a traditional operating room require an anesthesiologist to administer sedation, not general anesthesia. Generally, the sedating drugs are administered by injection and not by inhalation. Because no drugs are administered by inhalation, the anesthesia machine is not required and remains a fixture only in the traditional hospital operating room. The patient breathes on his own during the procedure.
Often the patient stops breathing and needs to be resuscitated with a bag-valve-mask, such as an AMBU® bag, (AMBU® is the registered trademark of AMBU A/S, Ballerup, Denmark) to start breathing again. The patient has been breathing on his own up to this point and the respiratory system is not coupled to any mechanical ventilation device.
The bag-valve-mask is the only tool available in most surgical suites and offices and it is very limited in function. The bag-valve-mask and valve is coupled to either a face mask secured to the patient's face or through an endotracheal tube. Ambient air is pushed into the lungs through a one-way valve when the bag is compressed by anesthesiologist or assistant. Once the bag has emptied into the lungs and released, it inflates from the other end and the air in the lungs is automatically expelled into ambient air, the bag-valve-mask constituting an open circuit system. The bag is compressed again for the next breath.
The amount and pressure of air entering the lungs is determined by the person compressing the bag. Generally bag-valve-masks are without any gauges, so only the experience and skill of the person compressing the bag protects the patient's lungs from over-inflating or over-pressurization. The person compressing the bag can only tell by external signs that the lungs are inflating properly, that air is not leaking from the mask or tracheal tube and the patient is properly being resuscitated.
The bag-valve-mask is further limited in mask ventilation situations when the patient has anatomic airway anomalies or is obese so that the mask does not fit tightly and seal around the nose and mouth. Without any gauges, the bag-valve-mask does not provide any objective method to assess adequacy of ventilation. In this situation, inadequate ventilation can lead to hypoxia and brain death.
While these units may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present disclosure as disclosed hereafter.
In the present disclosure, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which the present disclosure is concerned.
While certain aspects of conventional technologies have been discussed to facilitate the present disclosure, no technical aspects are disclaimed and it is contemplated that the claims may encompass one or more of the conventional technical aspects discussed herein.